Fibrous textile products



United States Patent 3,386,797 FIBROUS TEXTILE PRODUCTS Fabian T. Fang, Fox Point, Wis., assignor to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 846,776, Oct. 16, 1959. This application July 19, 1965, Ser. No. 473,169 The portion of the term of the patent subsequent to Nov. 19, 1980, has been disclaimed 5 Claims. (Ci. 8115.7)

This application is a continuation-in-part of my copending application Ser. No. 846,776, filed Oct. 16, 1959, now abandoned. The present invention is concerned with the production of fabrics formed of mechanically interlocked fibers, filaments, yarns and/or threads.

It is an object of the present invention to provide novel and improved fabrics for textile and industrial uses comprising fibers of sulfonated polymers of monovinyl aromatic compounds. One object is to provide fabrics comprising this type of fiber or filament which are characterized by resistance to the development of static electricity by rubbing or other mechanical action. Another object of the invention is to provide fabrics comprising this type of fiber having desirable dyeing and moistureregain qualities. Another object of the invention is to provide fabrics of this type of fiber which are characterized by both good tenacity and toughness. Another object of the invention is to provide fabrics which are adapted to be used as ion-exchange media and which in such use do not undergo excessive swelling in aqueous media. Another object of the invention is to provide fabrics of the various types stated which have outstanding durability under normal conditions of usage including not only normal textile wear, but also such industrial usage as requires repeated subjection to aqueous liquids with or without intervening drying. These objects and other advantages of the invention will be apparent from the description thereof hereinafter.

In accordance with one preferred embodiment of the present invention, certain fibers formed from polymers of monovinyl aromatic compounds are assembled or fabricated into various types of fabrics including those involving interlocked yarns or threads formed of plied yarns and those of felt-like character in which the fibers or filaments are interlaced or interlocked with or without being adhesively bonded at their points of intersection or interlocking. The former type of fabric may be a Woven, knitted, netted, knotted, or braided fabric formed of yarns comprising fibers or filaments of the type specified. Fabrics contemplated by the present invention are also obtainable by the haphazard distribution of a multiplicity of fibers either of short lengths or of continuous length. This includes such fabrics as are obtained by carding, and if desired, superimposing a plurality of carded webs upon one another with the machine direction of the various webs disposed either parallel to one another or at various angles for the purpose of providing either anisotropy or approximate isotropy in the characteristics of the resulting fabric, particularly as to strength and cleavage. Intermediate forms, which may also be termed hybrid forms, of fabrics may be involved such as the type of fabric known as needle felts wherein a woven or knitted fabric has fibers or filaments punched through the Woven base fabric.

The various fabrics may be formed entirely of fibers, filaments, and yarns of the polymeric monovinyl aromatic compounds or they may comprise a blend of fibers or filaments of this type with fibers or filaments of other types, either natural or artificial in origin. Similarly, the fabrics may be formed of a mixture of yarns comprising 3,386,797 Patented June 4, 1968 fibers or filaments of polymeric monovinyl aromatic compounds with yarns formed of other fibers, either natural or artificial. Thus, the fabrics may comprise, besides fibers of the polymeric monovinyl aromatic compounds, fibers, filaments, or yarns of cotton, wool, silk, linen, nylon, polyethylene glycol terephthalate (e.g., Dacron), regenerated cellulose rayons, cellulose acetate, casein, vinyl resin fibers, such as copolymers of vinyl chloride and vinyl acetate or acrylonitrile, and especially polymers containing from to 95% by weight of acrylonitrile such as Orlon and Acrilan. The proportion of fibers, filaments or yarns formed of the polymerized monovinyl aromatic compound in the fabrics may vary widely from 1 to 100%. For some purposes, a proportion of 1 to 10% may be entirely adequate such as in modifying the resistance to static electricity. In other fabrics, proportions of over 10%, such as from 15 to 50% may be desired; whereas for the preparation of industrial fabrics intended for ion-exchange purposes, the proportion is preferably over 50% such as from to 100%.

Among the fabrics contemplated by the present invention are those in which there may be a reinforcing element to improve the strength of the fabric in various ways. This reinforcing element may be, for example, a glass yarn woven at intervals through a woven fabric comprising the yarns formed of fibers of the present invention arranged in alternate relationship with the glassfiber or filament yarns. Pile and other tufted fabrics are also contemplated which may be formed entirely of the fibers comprising polymeric monovinyl aromatic compounds or partly thereof. For example, the fabric may be formed of a base or backing fabric, especially a woven fabric, made of reinforcing yarns such as of glass filament yarns, and a pile, or some or all of the tufted portion of the fabric, formed of the fibers or filaments of the polymerized monovinyl aromatic compounds.

The fabric may comprise potentially adhesive fibers adapted to bond fibers in the fabric together as a result of being rendered tacky by application of heat or s0lvents or both. The vinyl resin fibers such as copolymers of vinyl chloride and vinyl acetate are representative of this type of element.

An essential feature of the fabrics so far described which are employed for making the fabrics of the present invention is that they comprise at least 1% of fibers or filaments formed of certain linear addition polymeric monovinyl aromatic compounds. The polymerized monovinyl aromatic compounds of which the fibers are made must, in order to be converted into the sulfonated products of the present invention, contain a substantial amount of a linear polymerization product of a linear aliphatic polyene monomer or of an alkenyl halide monomer.

The monovinyl aromatic compound may be copolymerized with the linear aliphatic polyene monomer or with the alkenyl halide or with a mixture thereof; and if the fibers are formed exclusively from such a copolymer, the copolymer should be such that it has an apparent second order transition temperature, herein designated T which is at least about 20 C. and may be as high as 100 C. or more. Depending upon the particular polyene or the particular alkenyl halide or both present in the copolymer, the minimum amount of monovinyl aromatic compound required to provide the T of 20 C. or higher may vary. In general, however, the copolymers contain from 50 to by weight of a monovinyl aromatic compound.

The fiber may also be formed of a blend of a homopolymer of a monovinyl aromatic compound with a linear homopolymer of a linear aliphatic polyene or of an alkenyl halide. Again, the fiber may comprise (1) a copolymer of one or more monovinyl aromatic compounds or a copolymer of one or more vinyl aromatic compounds with one or more linear aliphatic polyenes or one or more alkenyl halides, and (2) a linear homopolymer or copolymer of a linear aliphatic polyene or alkenyl halide with or without other comonomers which may include one or more monovinyl aromatic compounds of the same or different species or type present in the first-mentioned polymer. In this type of blended polymer fiber, the apparent second order transition temperature, T of the blend should be at least about 20 C. and may be as high as 100 C. or higher.

In the fabrics mentioned above there may be used fibers in which the proportion of linear aliphatic polyene compound or of alkenyl halide or of both when both are present in the copolymer or blend is at least 1% by Weight of the copolymer or of the blend. There may also be used fibers formed from polymers in which the proportion of the polyene or alkenyl halide is as high as 50% by weight of the mixture in some instances provided the T of the copolymer or blend is at least about 20 C. Optimum results are obtained with fibers formed of polymers in which the proportion of the polyene or alkenyl halide is from to 20% by weight of the polymerized mass whether a copolymer or blend makes up the fiber.

The monovinyl aromatic compound which may also be termed a mono-alkenyl aromatic compound may be any of those having the formula wherein R is hydrogen or an alkyl group advantageously of less than 3 carbon atoms and Z is an aryl group which has positions on an aromatic nucleus available for substitution. The formula includes vinyl aryls, such as styrene, vinyl naphthalene, vinyl diphenyl, vinyl fiuorene, etc., and their nuclear-substituted derivatives such as alkyl, aryl, alkaryl, aralkyl, cycloalkyl, alkoxy, aryloxy, chloro, fluoro, chloromethyl, fiuoromethyl, and trifluoromethyl nuclear derivatives, for example methyl-styrenes, e.g., o, m, and p-methyl-styrenes, o, m, and p-ethyl styrenes, isopropyl-styrenes, tolyl-styrenes, benzyl-styrenes, cyclo hexyl-styrenes, methoxy-styrenes, phenoXy-styrenes, o, m, and p-chloro-styrenes, o, m, and p-fluorostyrenes, chloromethyl-styrenes, fiuoromethyl-styrenes, trifluoromethylstyrenes, vinyl-methyl-naphthalenes, vinyl-ethyl-naphthalenes, vinyl chloro naphthalenes, vinyl-methyl-chloronaphthalenes, etc. The polymerizable monomers which can be used advantageously with ionic type catalysts include aromatic compounds having a vinyl group containing an alkyl group in its alpha-position, e.g., isopropenyl or alpha-methyl-vinyl, alpha-ethyl-vinyl, alphapropyl-vinyl, etc. Such alpha-alkyl-vinyl groups may be substituted on benzene, naphthalene, diphenyl, fiuorene nuclei, etc., and may have other substituents on the aromatic nuclei as illustrated above for the vinyl aryl compounds.

Examples of linear aliphatic polyenes which may form parts of the copolymer or of homopolymers or copolymers in blends are butadiene-1,3; isoprene or 2-methylbutadiene-1,3; 2,3-dimethyl-butadiene-1,3; Z-methyl-pentadiene 1,3; hexatriene 1,3,5; myrcene; ocimene; alloocimene; etc., and certain substituted aliphatic polyenes such as chloro, fluoro, and aryl derivatives, e.g., chloroprene or 2-chloro-butadiene-1,3; fiuoroprene or 2-fluorobutadiene-1,3; and 1-phenyl-butadiene-1,3.

Examples of alkenyl halides which may be present in the copolymer or homopolymers or copolymers in blends making up the fibers are methallyl chloride, allyl chloride, 2,3-dichloro-propene-l, crotyl chloride, vinyl chloride, vinylidene chloride, 1-chloro-l-fluoro-ethylene, and 4-chloro-butene-1, pentenyl-chlorides.

In order to prepare the sulfonated fabrics of the present invention, the fabrics described above comprising at least 1% -by weight of fibers, filaments, or yarns formed of the polymerized aromatic compounds are treated to react the polymeric molecules in the fibers so that they become cross-linked. This treatment is effected by means of an alkylation catalyst. The reaction essentially involves the alkylation of the aromatic nuclei either (1) with the unsaturated portion of the linear polymer when a polyene is involved or (2) with the polymerized alkenyl halide by the elimination of hydrogen halide from the polymerized alkenyl halide units when such units are involved, or (3) with both (1) and (2). This alkylation cross-linking action may be effected by the use of Lewis acids or Friedel-Crafts catalysts such as aluminum chloride, ferric chloride, stannic chloride, titanium chloride, the corresponding bromides such as aluminum bromide and so forth, and boron trifluoride, especially its complexes such as with ethyl ether. Instead of the catalysts just mentioned, the alkylation can be effected simply by treatment with strong acids such as sulfuric acid, phosphoric acid, butyl phosphoric acid, chlorosulfonic acid, alkyl or aromatic sulfonic acids such as oor p-toluenesulfonic acid, or methanesulfonic acid, and polyphosphoric acid.

' The treatment with the Lewis acid catalysts may be efiected in solvents such as nitrornethane when such catalysts are of solid character; but when the liquid form such as the boron trifluoride ethyl ether complex is employed, no solvent need be used though if desired, a suitable solvent may be employed. In this procedure of operation, when a solvent is employed the tendency of the fibers to shrink in the solvent can be substantially completely prevented by employing the Lewis acid catalyst at a very high concentration therein or if desired, by holding the fibers under tension during treatment. The necessity to hold the fibers under tension is practically eliminated when concentrations of the catalyst in the neighborhood of one mole per liter or higher are used.

The temperature of treatment may range from 0 to C. when the Lewis acid catalyst is employed. In general, the time of treatment varies inversely with the temperature and it may range from about one minute up to two hours at the higher temperature above and for about 1 to 72 hours at the lower temperature. The treatment can be allowed to proceed for longer times than specified but ordinarily such additional treatment provides no additional benefit.

In the case of employing strong acids, such as the commerical 96% by weight sulfuric acid, temperatures may range from about 0 to 35 C. In the case of sulfuric acid, the concentration may vary from 70 to 103%. The time of treatment may vary from about 1 to 5 minutes at about 20 C. depending upon the denier of the fiber, the finer the fiber the shorter the time needed to provide etfective cross-linking and stabilization. At 0 C. a minimum period of about 10 to 15 minutes is generally needed to effect adequate cross-linking. Temperatures higher than 35 C. should be avoided since above that temperature sulfonation is favored which leads to swelling and dissolution of the fiber before cross-linking is adequately performed. With proper control of the temperature to prevent too rapid sulfonation, the treatment may be allowed to proceed for 3 or 4 days without causing shrinkage or dissolution of the fiber during the treatment.

The above cross-linking by alkylation, when effected by sulfuric acid or oleum or in the sulfonic acids, may introduce a certain proportion of sulfonic acid groups; and if the temperature is elevated sufiiciently, an adequate amount of sulfonation may be effected for the purposes of the invention. Thus, the alkylation treatment may involve the introduction of as much as 0.1 to 0.5 sulfonic acid group per aromatic nucleus in the polymerized aromatic fiber. This provides sufiicient modification for improved dyeing, improved hand by virtue of moisture regain, and improved resistance to the development of static electricity. However, for many purposes, sulfonation is effected by an extension or continuation of the alkylation treatment or by an additional after-treatment with a sulfonating agent. This sulfonation, as stated, can be a con- 5 tinuation of the alkylation treatment when that is done by means of sulfuric acid or one of the strong sulfonic acids mentioned hereinabove and such continuation is preferably carried out at temperatures elevated above the upper limit of 25 C. set out above for the alkylation treatment.

If desired, the sulfonation may involve the addition of the more strongly acting sulfonating agent than the sulfuric acid employed during the cross-linking stage. Thus, oleum may be added to the sulfuric acid bath in stages. This extended sulfonation may be carried out at room temperature or up to 100 C. or even as low at C. This time depends upon the temperature and the particular sulfonating agent. Chlorosulfonic acid is extremely rapid in its action even at 0 'C. When sulfur trioxide is employed as a sulfonating agent, a solvent such as dioxane may be employed.

The extended treatment with sulfuric acid or fuming sulfuric acid may be accelerated by the employment of catalysts such as silver sulfate.

When the alkylation is effected by means of a Lewis acid or of a phosphoric acid or other strong acid other than a sulfonating type, it is merely necessary to add a sulfonating agent with or without such a catalyst as silver sulfate to the cross-linking bath to effect the sulfonation.

If the desired extent of sulfonation has been effected, the fibrous product is removed from the sulfonating bath and washed or rinsed. This may desirably be effected by treatment with two or more increasingly dilute sulfuric acid or other sulfonating acid solutions in water. Then, the treated fabric may be finally washed and if desired, neutralized in an aqueous alkaline solution.

By the procedure of the present invention, ion-exchange fabrics may be obtained which are highly sulfonated and yet are not subject to excessive swelling or shrinkage in aqueous media during use as ion-exchangers. The extent of sulfonation may be anywhere from 0.1 to 3 sulfonic acid groups per aromatic nucleus. The ion-exchange capacity may range from about 0.5 milliequivalent per gram to 5 milliequivalents per gram. Preferred products have ion-exchange capacity from 3 to 5 milliequivalents per g am.

Instead of treating the fabrics formed of the fibers or filaments of polymerized aromatic compounds to convert them to cross-linked and sulfonation products, which constitutes the preferred embodiment so far described, the fibers, filaments, or yarns of the polymerized monovinyl aromatic compounds containing the polyene or alkenyl halide copolymerized or blended therein may be subjected to the cross-linking by alkylation and then fabricated into the desired fabric which is in turn subjected to a final sulfonation treatment (unless the desired amount of sulfonation occurred during the alkylation treatment of the fibers, filaments, or yarns). Still another alternative which, however, is less preferable is the cross-linking and sulfonation of the fibers, filaments, and yarns followed by the fabrication of the desired fabrics from the sulfonated fibers, filaments, or yarns.

Another essential feature of the fibers, filaments, and yarns from which the fabrics of the present invention are obtained is the fact that they have been stretched (before cross-linking by alkylation) at least and preferably at least 50% in terms of their original length on initial production. Such stretching may be as high as several thousand percent of such original length. The stretching orients the polymer molecules in the fibers and by having the fibers in the stretched condition at the time they are cross-linked by the alkylation treatment, strong, tough fibers and fabrics are obtained. It is a surprising fact that the alkylation treatment increases the strength and tough ness of the fibers, filaments, and yarns as compared to these qualities in the stretched fibers, filaments, or yarns which are treated.

The fibers or filaments as well as the yarns of the polymerized monovinyl aromatic compounds required in the fabrics used as the starting materials of the present invention can be made by the extrusion, through a spinneret having an orifice or a plurality of orifices having a diameter of about 0.001 to 0.005 inch into a suitable coagulating medium, of either a molten mass of the polymeric mass to be formed into the fiber or of a solution or aqueous dispersion thereof. The polymers may have molecular weights from 10,000 up to 10,000,000. Preferably, they have molecular weights of 300,000 or higher. The polymers or copolymers may be produced by any suitable polymerization system such as bulk, solution, emulsion, or suspension. When a blend of a polymer of the monovinyl aromatic compound with a linear copolymer of a linear aliphatic polyene or of an alkenyl halide is used for extrusion, the blend may be made by mixing molten masses of separately produced polymers. The blend may be produced by mixing solutions of separately produced polymers which may be the solutions obtained directly in the polymerization, or the blend may be produced by mixing aqueous dispersions obtained by the separate emulsion polymerization of the two components. The blending of such aqueous dispersions has the advantage that it is relatively easy to produce extremely high molecular weight polymers of the monovinyl aromatic compound. When the monovinyl aromatic compound is copolymerized with an alkenyl halide or with a polyene, the latter constituents tend to reduce the molecular weight obtainable.

The polymeric spinning mass may be formed into fibers in any suitable way such as by extruding a molten mixture into an atmosphere having a controlled temperature and especially a temperature substantially below the melting point of the mixture.

The fibers may be formed by extruding a solution of the polymer blend in an organic solvent into a coagulating medium which may be a heated or cooled atmosphere in the case of a dry spinning system, or a liquid coagulating bath in the cast of a wet spinning system. An aqueous dispersion of a blend of emulsion polymers may likewise be spun in either a dry or wet spinning system. In a wet spinning system, the coagulating bath is composed of a liquid medium which is not a solvent for the polymer blend but is a solvent for the solvent that is used in making the solution of the polymer that is spun. In the spinning operation by dry or wet spinning, the polymer blend is subjected to an operation for effecting complete coalescence. This may involve simply the maintenance of a sufficiently high temperature in the coagulating medium or it may involve a separate step thereafter in which the partially coalesced polymer blend is completely coalesced by heat. The temperature for this purpose may be from 60 to 400 C. dependin upon the particular polymer blend to be coalesced.

After coalescence of the polymer blend into the fiber form, it is necessary to subject the filament or fiber to stretching. The stretching may be as low as 10%, but is preferably from 50% to several thousand percent of the initial length obtained after coalescence. This stretching may be facilitated by carrying it out on the filaments ilyzhle Csjubjected to a temperature in the range of 40 to As pointed out hereinabove, the products of the present invention are quite advantageous and have a wide variety of uses. In textile products, the presence of 5 to 50 sulfonic acid groups per aromatic nuclei in the polymerized monovinyl aromatic compound in the fiber imparts advantageous moisture-regain properties and reduces the tendency to develop static charges on rubbing. This latter property is extremely important in the production of automobile seat covers. Fabrics comprising fibers having 50 to 300 or more sulfonic acid groups per 100 aromatic nuclei in the polymerized monovinyl aromatic compound of the fiber are advantageous in numerous uses. They are useful as wash cloths (for both faceand dish-washing purposes) in which utility they soften the water that is employed. They may, of course, be readily regenerated by soaking in an acid medium. The pile and tufted fabrics are particularly useful when they contain sulfonic acid groups in the larger range specified for use as ion-exchange media. The pile or height of tuft in such fabrics may vary extensively. Generally, a thickness of 0.05 to 1 inch or more is quite advantageous.

In the examples which are illustrative of the invention, the parts and percentages are by weight unless otherwise indicated.

Example A illustrates a method by which the stretched fibers of a polymeric monovinyl aromatic compound may be produced.

EXAMPLE A Two emulsion polymers are prepared in aqueous dispersions using 3% potassium laurate based on solids in each case, the first being polystyrene and the second polybutadiene both at 40% polymer solids by Weight. The two dispersions are blended in an 85:15 styrene-to-butadieneweight ratio and 5% toluene based on polystyrene solids is gradually added with stirring. The dispersion blend is forced through a platinum-alloy spinneret into a coagulating bath. The spinneret has a face diameter of 0.5 inch and contains 100 holes each of 0.0025 inch diameter. The coagulating bath is an aqueous 30% hydrochloric acid solution also containing 0.5% p-diisobutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride and is maintained at 85 C. The bundle of filaments formed is drawn through the bath at a rate of about eleven meters per minute. The immersion path is four inches. The yarn is washed on a roll immersed in a trough fed by fresh water and equipped with an overflow pipe. The yarn is then dried by passing it over two canted heated drums revolving at a speed providing a linear peripheral rate of about 11 meters per minute. The temperature of the drums is 230 C. The yarn is then passed over rolls operating at differential speeds to stretch the yarn about 500%. The first of these two rolls is heated to about 120 C. The stretched yarn is collected on a bobbin winder. It has a denier of about 200, a tenacity of 0.9 gram per denier, and an extensibility of 25% at break.

EXAMPLE 1 (a) Skeins of a yarn formed of continuous filaments (200 denier, 100 filament) of a blend of 85 parts of polystyrene and 15 parts of polybutadiene which had been stretched about 500% during manufacture (obtained as in Example A) is immersed in 95% sulfuric acid at 25 C. for one day. The treated skeins are then rinsed in water and dried by exposure to the ambient atmosphere. The resulting yarn is insoluble in organic solvents so that it is dry-cleanable. It is also entirely resistant to shrinkage at temperatures up to and including 200 C. so that it can be scoured without risk of shrinkage. As a result of the treatment, the tenacity is increased by about 50% and the toughness is increased by about 500%. The fibers contain about 2 to 3 sulfonic acid groups per 100 aromatic nuclei in the polymeric mass of which they are formed, rendering the product resistant to the development of static charges.

(b) A portion of the yarn obtained in part (a) is wound upon a warp beam and a portion thereof is wound upon shuttle bobbins. The warp beam and the shuttle bobbins are mounted on a loom by means of which the yarn is woven into an 80 x 80 fabric. The resulting fabric is highly resistant to the development of static charges and is characterized by a pleasant feel because of the hydrophilic groups therein.

(0) A pile fabric is produced using glass fiber yarns for the base fabric and, as the pile, threads obtained by doubling with low twist l0 ends formed of the yarn obtained by the treatment of Example 1(a). The pile fabric thus obtained is then immersed in 98% sulfuric acid at 50 C. for 24 hours. Thereupon, the fabric is removed, rinsed in sulfuric acid, and then rinsed in water. The product obtained has an ion-exchange capacity of about 5.0 milliequivalents per gram and is formed into an endless belt. This belt is used for removing cations by a continuous process from various media, e.g., for the softening of hard water. The belt is arranged in conventional fashion to proceed, under the driving action of sprockets or rolls, repeatedly in succession through the liquid form from which the cations are to be removed, then optionally through a rinse bath, and finally through a regenerating bath of acid such as 10% hydrochloric acid.

EXAMPLE 2 A yarn obtained as in Example A from a copolymer of by weight of styrene with 10% by weight of vinyl chloride is knitted into a tubular fabric having a diameter of approximately 3 inches. The knitted fabric thus obtained is subjected to a stabilizing alkylation by being padded through a 96% sulfuric acid bath at 40 C. for 15 minutes. Thereafter, the fabric is rinsed in water. The polymer of which the fibers in the fabric are for-med has about 2 sulfonic acid groups per 10 aromatic nuclei, providing an ion-exchange capacity of about 1.0 milliequivalent per gram. It is useful for supporting within its circumference a body of ion-exchange beads or of filtering material.

EXAMPLE 3 (a) A tow is formed of filaments of a copolymer of 85% by weight of vinyltoluene and 15% by weight of butadiene by a procedure essentialy that of Example A. The tow is chopped into fibers of 2-inch length and passed through a carding engine. A non-woven web is built up of five such carded webs in which the machine direction of alternate webs is set at 90 angles to the direction of adjacent webs. The resulting non-woven Web is passed through embossed rolls, one of which is heated and has a relief surface formed of two sets of lines ,6 inch wide intersecting at 90 angles, the lines in each set being spaced apart by a distance of approximately 1.75 inch. The temperature of the heated roll is approximately 90 C. so that fusion of fibers is caused in the vicinity of the contact made with the lines of the roll. The result is a non-woven fabric bonded along lines which intersect at right angles. The fabric is immersed in a 1.0 molar solution of aluminum chloride in nitromethane at 30 C. for 12 hours, thereupon rinsed, and air-dried. This treatment renders the non-woven fabric insoluble in organic solvents and resistant to shrinkage at temperatures up to and including 200 C. The treatment also increases the toughness by about 300%.

(b) The fabric thus obtained is suspended in a closed chamber wherein it is subjected to vaporized sulfur trioxide at room temperature for about 10 minutes. An exo thermic reaction occurs and a sulfonated product having an ion-exchange capacity of about 4.5 milliequivalents per gram is obtained. At the end of the 10-minute exposure, the fabric is removed, rinsed in 90% sulfuric acid, rinsed in water, and then air-dried.

EXAMPLE 4 A fabric is woven of yarn formed of a copolymer of 80% of vinyltoluene with 20% by weight of isoprene. The fabric is treated as in Example 1(a) hereinabove, thereby producing a stabilized fabric resistance to shrinkage, resistant to dry-cleaning, and having anti-static characteristics.

EXAMPLE 5 A 200,000-filament tow is formed of continuous filaments obtained by a spinning procedure similar to Example A from a blend of 90 parts of poly(vinyltoluene) and 10 parts of natural rubber, the filaments having been stretched 600% during the manufacture. The tow of filaments is cut to 2.5-inch lengths and the cut fibers are opened and then carded. The carded fibers are assembled into a 4-web thick laminate, then passed through heated embossed rolls, and subsequently treated (all as in Example 3), yielding an ion-exchange product adapted to be used for softening water and other ionexchange purposes, as wash-cloths, dish-cloths, and the like.

EXAMPLE 6 A yarn is formed of a copolymer of 80% by weight of styrene and 20% by weight of butadiene and cross-linked and sulfonated by treatment with concentrated sulphuric acid. The sulfouated product has an ion-exchange capacity of 2 milliequivalents per gram. The fiber is chopped up into 2-inch lengths and blended with varying amounts of a polyester fiber (a polyethylene terephthalate obtained under trademark Dacron). The electrical resistances of the various fiber blends are then determined by placing a pad of the fiber blend across two At-inch square electrodes placed a half-inch apart. The resistance is measured using the circuit described by Hayes and Chromey, American Dyestufi" Reporter 40, 225 (1951) while maintaining a stream of dry nitrogen through the instrument. The instrument measures resistances from 10v ohms to 10 ohms. The ambient humidity during these measurements is about 50% relative humidity. The weight ratios of polyester fiber to sulfonic fiber and the resistances in ohms of the blends are set forth in the following table.

Fiber: Resistance (ohms) Polyester fiber (100%) 10 Sulfoni-c fiber (100%) 10 75/25 7.1 10 90/10 3.5 10 95/5 2.2 10 99/1 2.2)(10 Cotton fiber 100% 4.5 10

The resistance of the sulfonic fiber is stable to repeated washings in distilled water using hand soap and using a commercial detergent available under the trademark Tide. A saturated solution of calcium chloride increases the resistivity.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. As an article of manufacture, a fibrous product having improved antistatic properties comprising a blend of (1) about 1% to 10% by weight of a fiber formed of linear polymer molecules, at least part thereof being formed of at least one monovinyl aromatic compound and at least part thereof being formed of at least one compound selected from the group consisting of linear aliphatic polyene monomers and alkenyl halides, the polymeric mass of which the fiber is formed having an apparent second order transition temperature of at least 20 C., the linear polymers showing orientation longitudinally of the axis of the fiber and being cross-linked in the fiber to a condition of solvent resistance by alkylation of aromatic nuclei by members selected from the group consisting of polymerized units of polyene and alkenyl halide compounds, said fiber containing at least one sulfonic group per 10 aromatic nuclei in the fiber, and (2) about 90% to 99% by weight of other fibers selected from the group consisting of natural and artificial fibers, said other fiber (2) having a surface electrical resistivity measured at relative humidity at least 10 ohms greater than said fiber (1).

2. An article of manufacture according to claim 1 wherein the fibrous product is a woven textile fabric.

3. An article of manufacture according to claim 1 wherein the fibrous product is a knitted textile fabric.

4. An article of manufacture as defined in claim 1 wherein the fibrous product is a pile textile fabric.

5. An article of manufacture according to claim 1 wherein said other fiber is selected from the group consisting of nylon, polyethylene terephthalate and cellulose acetate.

References Cited UNITED STATES PATENTS 2,595,977 5/1952 Peckham 57-157 2,845,962 8/1958 Bulgin 57157 2,937,066 5/1960 Walles. 3,001,264 9/1961 Bloch 57-157 3,008,215 11/1961 Pitts 57-157 3,055,729 9/1962 Richter et al. 2602.2 XR 3,111,359 11/1963 Fang. 3,111,360 11/1963 Fang. 3,111,361 11/1963 Fang. 3,111,362 1l/l963 Fang et al.

NORMAN G. TORCHIN, Primary Examiner.

H. WOLMAN, Assistant Examiner. 

1. AS AN ARTICLE OF MANUFACTURE, A FIBROUS PRODUCT HAVING IMPROVED ANTISTATIC PROPERLESS COMPRISING A BLEND OF (1) ABOUT 1% TO 10% BY WEIGHT OF A FIBER FORMED OF LINEAR POLYMER MOLECULES, AT LEAST PART THEREOF BEING FORMED OF AT LEAST ONE MONOVINYL AROMATIC COMPOUND AND AT LEAST PART THEREOF BEING FORMED OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF LINEAR ALPHATIC POLYENE MONOMERS AND ALKENYL HALIDES, THE POLYMERIC MASS OF WHICH THE FIBER IS FORMED HAVING AN APPARENT SECOND ORDER TRANSITION TEMPERATURE OF AT LEAST 20* C., THE LINEAR POLYMERS SHOWING ORIENTATION LONGITUDINALLY OF THE AXIS OF THE FIBER AND BEING CROSS-LINKED IN THE FIBER TO A CONDITION OF SOLVENT RESISTANCE BY ALKYLATION OF AROMATIC NUCLEI BY MEMBERS SELECTED FROM THE GROUP CONSISTING OF POLYMERIZED UNITS OF POLYENE AND ALKENYL HALIDE COMPOUNDS, SAID FIBER CONTAINING AT LEAST ONE SULFONIC GROUP PER 10 AROMATIC NUCLEI IN THE FIBER, AND (2) ABOUT 90% TO 99% BY WEIGHT OF OTHER FIBERS SELECTED FROM THE GROUP CONSISTING OF NATURAL AND ARTIFICIAL FIBERS, SAID OTHER FIBER (2) HAVING A SURFACE ELECTRICAL RESISTIVITY MEASURED AT 50% RELATIVE HUMIDITY AT LEAST 10**5 OHMS GREATER THAN SAID FIBER(1). 